In United States network television programming, a hiatus is a break of several weeks, months or years in the normal broadcast programming of a television series. Such a break can occur part-way through the season of a series, in which case it is also called a mid-season break, or between distinct television seasons (usually starting in June and ending in September, when shooting starts for the next season). In the Northern Hemisphere, the breaks between late November and early February are also referred to as winter breaks or, in the Christian cultural sphere, Christmas breaks. Until the late 1990s, summer breaks were sometimes replaced by summer replacement series. Planned hiatus Most broadcast network television series are scheduled for a season of 22 episodes in a time span running 36 weeks from September to May, so networks usually arrange the 22 episodes to air in blocks. Television stations often implement a hiatus for their programs to split up a season for storyline purposes. Some programs also go on hiatus so that their television networks can reserve episodes for airing during the three major ratings sweeps periods, wherein networks compute their television advertising fees based on their programs' ratings during that period. Programs return from a hiatus in time for the sweeps period so as to generate high ratings, and as such usually include special content in programming such as guest stars, controversial and unexpected plots or topics, extended episodes, and finales. Television programs tend to have a hiatus for the late-November, throughout December and early January holidays or the summer if the season does not end before, resuming at some point after, most often early February in the case of Christmas and New Year, and September in the case of the summer. In the United States, hiatuses may also be common during major sporting events - currently Major League Baseball playoffs in October for Fox, the Olympic Winter Games in February quadrennially on NBC, and the NCAA Division I men's basketball tournament in March for CBS, and for Sunday programs, throughout the winter awards season. The American mid-season break usually starts at Thanksgiving in late-November, sometimes ending with a Thanksgiving or Christmas episode, and lasts until the Super Bowl the first Sunday in February. The final episode airing before the Christmas break is usually referred to as the midseason finale, or in the northern hemisphere, "winter finale". At this time, other